1. Field of the Invention
The invention relates to a partially sulfonated polybenzimidazole based polymer, method for preparing the same, a membrane electrode assembly for fuel cell using the polybenzimidazole based polymer and method for preparing the same.
2. Description of the Related Art
Polybenzimidazole based polymers are being studied for replacing the Nafion®-type perfluorosulfonic acid in a field of fuel cell membrane.
Some polybenzimidazole based polymers such as poly[2,2-(m-phenylene)-5,5-bibenzimidazole] (PBI) or poly[2,5-benzimidazole] (ABPBI) are doped with inorganic acids for improving their mechanical strength or chemical stability.
However, the cell performance using the polybenzimidazole based polymers are still low compared to those using the Nafion®-type perfluorosulfonic acid.